Common Courtesy - Unglued - 21

Enchantment

Mana Cost: {2}{U}{U}

Whenever a player casts a spell without asking your permission while casting it, counter that spell.
When a player asks you permission to cast a spell and you refuse, counter that spell and sacrifice this enchantment.

Uncommon · Unglued · #21 (UGL)

Illustrated by Mike Raabe